Exhaled lipids associate with asthma and its severity

Published Online: April 22, 2013

Lipid mediators such as lipoxins and leukotrienes are released in the human airway during cell-cell interactions. Lipoxins are mediators that counteract leukotriene-mediated inflammation and thus help to maintain tissue homeostasis. Inadequate lipoxin production and its impaired function are associated with more severe asthma.

In their article published recently in The Journal of Allergy & Clinical Immunology (JACI), Kazani et al hypothesized that they could analyze non-invasively obtained exhaled breath condensate (EBC) for lipoxins and leukotrienes and use these measurements to serve as non-invasive biomarkers for the diagnosis of asthma and assessment of its severity. The authors describe the analysis of exhaled breath condensates collected from healthy controls and patients with varying degrees of asthma severity. EBC was collected over 10 minutes.

The investigators found that EBC lipoxin A4 (LXA4) and leukotriene B4 (LTB4) levels were elevated more than 10-fold in the patients with asthma when compared to healthy controls. However, the relative proportion of EBC LXA4 diminished significantly with increasing asthma severity. The EBC LXA4/LTB4 ratio was 41% lower in severe asthmatics as compared to those with moderate disease. They identified a strong association between EBC LXA4 levels and airflow obstruction measured by FEV1% predicted. They also determined that the cut off levels of 7 and 11 pg/ml of LXA4 and LTB4 respectively, were highly sensitive and specific for the diagnosis of asthma.

The investigators conclude that production of pro-inflammatory lipids in asthmatic airways is accompanied by simultaneous activation of the pro-resolving lipid pathway. Measurement of representative mediators from these pathways in a non-invasive manner from exhaled breath provides a clinically applicable, sensitive, and specific tool for the diagnosis of asthma. The proportion of pro-resolving lipoxins in the lungs decreases with increasing asthma severity, suggesting that replacing these compounds may present a therapeutic option in the management of severe asthma.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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